1. Field of the Invention
The present invention relates to a liquid jet recording head for used with an ink jet recording system to generate small recording liquid droplets, a method for manufacturing such a recording head, and a recording apparatus having such a recording head.
2. Related Background Art
Liquid jet recording heads used with ink jet recording systems (liquid jet recording systems) generally comprise small recording liquid discharge openings, liquid passages, and liquid discharging energy generating portions disposed in the liquid passages. An example of a method for manufacturing such conventional liquid jet recording heads is disclosed in the Japanese Patent Application Laid-open No. 57-43876. More particularly, in this conventional method, a photosensitive compound layer (for example, negative tipe dry film LAMINAR (manufactured by DYNA CHEMICAL Co.), SR-1000G-50 (manufactured by HITACHI KASEI Co., Ltd.), SR-1000N (manufactured by HITACHI KASEI Co., Ltd) or the like) is deposited on a substrate on which energy generating bodies are arranged, and then hardened or cured areas are formed by performing predetermined pattern exposure. Thereafter, ink liquid passages (also referred to as xe2x80x9cnozzlesxe2x80x9d hereinafter) are formed on a surface of the substrate by removing the non-cured compound from the photosensitive compound layer. Further, a liquid chamber forming member (lid plate) is bonded to the surface of the substrate via an adhesive layer to form two pairs of liquid jet recording heads. Thereafter, the assembly is cut by a diamond blade to separate two pairs of heads and at the same time to form liquid discharge openings, thereby obtaining individual liquid jet recording heads. According to this conventional method, it is possible to form the liquid passages very uniformly and to manufacture the heads in great quantities, since the photo-lithographic technique can be used.
However, this conventional method has the following drawbacks.
(1) In steps from a nozzle forming step to a cutting step, particularly, in the cutting step, cut powder and/or dirt in a cutting liquid enter into the nozzles, thus worsening the yield rate.
(2) During the cutting operation, a so-called xe2x80x9cchippingxe2x80x9d occurs around the discharge openings, which causes the incorrect discharging direction for the recording liquid droplets, thereby deteriorating the recording quality and worsening the yield rate. The xe2x80x9cchippingxe2x80x9d means a phenomenon that edges of the discharge openings are broken during machinging operations such as the cutting of the discharge openings, the polishing of the discharge openings and the like.
(3) In order to prevent the occurrence of the pitching during the cutting operation, a diamond blade of resin bond type must be used. However, such a diamond blade makes the cutting speed slower and the cost of the cutting operation more expensive. Further, since such diamond blade is worn away relatively rapidly, it is difficult to control the accuracy (normally, about xc2x110 xcexcm) of the head.
(4) Particularly, in heads of high density multi-array type (i.e., type wherein a multiple of nozzles are arranged along an elongated width of A4 or A3 size), it is very difficult to form all of the nozzles correctly.
In order to eliminate the above-mentioned conventional drawbacks, the following method has been proposed. That is to say, a solid layer is deposited on a substrate at locations where nozzles are to be formed, and the solid layer is covered by a layer made of active energy ray curable material (nozzle forming material) and then a liquid chamber forming member is arranged on such layer. Then, the active energy ray curable material is cured by the active energy rays. Thereafter, the assembly is cut by a diamond blade at a high speed to separate two pairs of heads. Then, a discharge opening surface is polished to remove the pitching generated during the cutting operation, thereby finishing the discharge opening surface. Finally, by dissolving the solid layer by a removing liquid to remove the solid layer, thereby forming the nozzles.
According to this method, in the steps from the nozzle pattern forming step to the polishing step, since the interior of each nozzle is filled by the solid layer, the dirt can be prevented from being enter into the nozzles during such steps. Further, since the polishing operation is used, it is no need to prevent the pitching during the cutting operation, thereby permitting the faster cutting operation. This is effective, particularly in the manufacture of the head of high density multi-array type.
However, this conventional method still arises a problem that the broken portions (at about 10 points) are generated around the discharge openings in the manufacture of the head of high density multi-array type, although the occurrence of the pitching can be greatly suppressed. (The total number of nozzles is about 4700 in a head having the nozzle density of 400 DPI and a dimension of A3 size; thus, if the broken portions are 10, the rate of occurrence of the broken portion per nozzle will be about 0.2%).
An object of the present invention is to provide a unique method for manufacturing a liquid jet recording head, which can eliminate the above-mentioned conventional drawbacks and which is particularly effective in the manufacture of a liquid jet recording head of high density multi-array type.
In order to achieve the above object, according to an aspect of the present invention, there is provided a method for manufacturing a liquid jet recording head wherein a solid layer having at least one liquid passage pattern and made of resin soluble in a solid layer removing liquid, and a liquid passage wall forming material layer for covering the solid layer are interposed between a substrate and a lid plate to form a liquid jet recording head sub-assembly, then, the sub-assembly is cut at a discharge opening forming portion, and then the cut surfaces are polished, and thereafter the solid layer is removed, and wherein, before the polishing step, the solid layer is cured up to the pencil hardness H or more.
According to another aspect of the present invention, there is provided a method for manufacturing a liquid jet recording head wherein a photosensitive compound layer is laminated on a substrate, then liquid passages are formed, and then a lid plate is laminated on the compound layer to form a liquid jet recording head sub-assembly, and thereafter a filler is loaded into the liquid passages, and then the cutting operation, polishing operation and filler removing operation are successively performed, and wherein, before the polishing operation, the filler is cured up to the pencil hardness H or more.
The present invention was created on the basis of the following knowledge.
That is to say, the inventors found that the chipping areas (broken portions) which generated during the polishing operation of the discharge opening surface were concentrated at the edges of the discharge openings. Since the solid layer has relatively low hardness (softer), it is considered that the foreign matters enter into the solid layer during the polishing operation to interfere with the edges of the discharge openings, thereby occurring the chipping. It is assumed that the reason why this fact was not remarked conventionally is that, since the solid layer provided in correspondence to the ink passages was to be finally removed in the liquid jet recording head, the softer solid layer (easy to remove) was preferable so long as it can ensure the dimension and configuration of the ink passages precisely.
In consideration of the above, the inventors found that the edges of the discharge openings having substantially no chipping could be obtained by increasing the hardness of the solid layer by curing the solid layer in correspondence to the ink passages to prevent the foreign matters from entering into the solid layer. On the basis of this knowledge, after various test and investigation, the inventors found that when the solid layer had the pencil hardness of H or more, preferably 2H or more, and more preferably 3H or more, the above effect could be satisfactorily obtained.
Incidentally, the pencil hardness is based on the test pencil hardness defined by the Japanese Industrial Standard K5400-6:14(3), and the test machine was in accordance with the Japanese Industrial Standard K5401. The testing method was in accordance with the Japanese Industrial Standard K6894.